18920561 has 8 divisors (see below), whose sum is σ = 21727200. Its totient is φ = 16295040.

The previous prime is 18920521. The next prime is 18920563. The reversal of 18920561 is 16502981.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18920561 - 2¹⁸ = 18658417 is a prime.

It is a Curzon number.

It is a nialpdrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (18920563) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45056 + ... + 45473.

It is an arithmetic number, because the mean of its divisors is an integer number (2715900).

Almost surely, 2^18920561 is an apocalyptic number.

18920561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18920561 is a deficient number, since it is larger than the sum of its proper divisors (2806639).

18920561 is a wasteful number, since it uses less digits than its factorization.

18920561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90559.

The product of its (nonzero) digits is 4320, while the sum is 32.

The square root of 18920561 is about 4349.7771207270. Note that the first 3 decimals coincide. The cubic root of 18920561 is about 266.4677591364.

The spelling of 18920561 in words is "eighteen million, nine hundred twenty thousand, five hundred sixty-one".